[gecode-users] Bugs in Gecode/J

[Guido Tack]

I'm now certain that it's the concurrent GC that's causing the  
problems (well, because of some bug in Gecode/J, of course).  You can  
easily work around it by running java with the -XX:-UseParallelGC  
option.

Cheers,
	Guido

Guido Tack wrote:

> Malcolm Ryan wrote:
>
>> I don't mean to hassle you, but I just need to know whether you think
>> you can help me with this problem. I am working towards a close paper
>> deadline and I need to know whether to stick with Gecode/J in the  
>> hope
>> that we will be able to sort out these problems, or whether I need to
>> look for another solution.
>
> I've run some more experiments, and I can finally reproduce your  
> bug.  It seems to be a memory management / concurrency issue.  I  
> could not reproduce the bug on any 1- or 2-core machine, but only  
> with at least 4 cores.  I suspect Java's concurrent garbage  
> collector frees some memory that is still in use because we didn't  
> get the locking right.
> Did you do all your experiments on multi-core machines (i.e., more  
> than 2 cores)?  If that's really the problem, you could run your  
> tests with a limit on the number of CPUs used.  On Linux, you can  
> achieve this using the taskset command.  On Mac OS 10.5, you can  
> follow this hint to get control of your processors:
> http://www.macosxhints.com/article.php?story=20071116183942199
>
> I hope this helps.  We'll try to figure out the real cause of the  
> problem, but concurrency bugs are typically hard to find - it may  
> take some time.
>
> Cheers,
> 	Guido
>
> _______________________________________________
> Gecode users mailing list
> users at gecode.org
> https://www.gecode.org/mailman/listinfo/gecode-users

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 2436 bytes
Desc: not available
URL: <http://www.ps.uni-sb.de/pipermail/users/attachments/20080421/6787301f/attachment.bin>